ARM: tegra: Core changes for v5.5-rc1

Contains two fixes for CPU idle and suspend/resume on early Tegra SoCs.
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Merge tag 'tegra-for-5.5-arm-core' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into arm/soc

ARM: tegra: Core changes for v5.5-rc1

Contains two fixes for CPU idle and suspend/resume on early Tegra SoCs.

* tag 'tegra-for-5.5-arm-core' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  ARM: tegra: Use WFE for power-gating on Tegra30
  ARM: tegra: Fix FLOW_CTLR_HALT register clobbering by tegra_resume()

Link: https://lore.kernel.org/r/20191102144521.3863321-5-thierry.reding@gmail.com
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-tegra/reset-handler.S

@@ -44,16 +44,16 @@ ENTRY(tegra_resume)
 	cmp	r6, #TEGRA20
 	beq	1f				@ Yes
 	/* Clear the flow controller flags for this CPU. */
-	cpu_to_csr_reg r1, r0
+	cpu_to_csr_reg r3, r0
 	mov32	r2, TEGRA_FLOW_CTRL_BASE
-	ldr	r1, [r2, r1]
+	ldr	r1, [r2, r3]
 	/* Clear event & intr flag */
 	orr	r1, r1, \
 		#FLOW_CTRL_CSR_INTR_FLAG | FLOW_CTRL_CSR_EVENT_FLAG
 	movw	r0, #0x3FFD	@ enable, cluster_switch, immed, bitmaps
 				@ & ext flags for CPU power mgnt
 	bic	r1, r1, r0
-	str	r1, [r2]
+	str	r1, [r2, r3]
 1:
 
 	mov32	r9, 0xc09

arch/arm/mach-tegra/sleep-tegra30.S

@@ -682,10 +682,12 @@ tegra30_enter_sleep:
 	dsb
 	ldr	r0, [r6, r2] /* memory barrier */
 
+	cmp	r10, #TEGRA30
 halted:
 	isb
 	dsb
-	wfi	/* CPU should be power gated here */
+	wfine	/* CPU should be power gated here */
+	wfeeq
 
 	/* !!!FIXME!!! Implement halt failure handler */
 	b	halted

drivers/soc/tegra/flowctrl.c

@@ -91,8 +91,23 @@ void flowctrl_cpu_suspend_enter(unsigned int cpuid)
 		reg &= ~TEGRA30_FLOW_CTRL_CSR_WFE_BITMAP;
 		/* clear wfi bitmap */
 		reg &= ~TEGRA30_FLOW_CTRL_CSR_WFI_BITMAP;
-		/* pwr gating on wfi */
-		reg |= TEGRA30_FLOW_CTRL_CSR_WFI_CPU0 << cpuid;
+
+		if (tegra_get_chip_id() == TEGRA30) {
+			/*
+			 * The wfi doesn't work well on Tegra30 because
+			 * CPU hangs under some odd circumstances after
+			 * power-gating (like memory running off PLLP),
+			 * hence use wfe that is working perfectly fine.
+			 * Note that Tegra30 TRM doc clearly stands that
+			 * wfi should be used for the "Cluster Switching",
+			 * while wfe for the power-gating, just like it
+			 * is done on Tegra20.
+			 */
+			reg |= TEGRA20_FLOW_CTRL_CSR_WFE_CPU0 << cpuid;
+		} else {
+			/* pwr gating on wfi */
+			reg |= TEGRA30_FLOW_CTRL_CSR_WFI_CPU0 << cpuid;
+		}
 		break;
 	}
 	reg |= FLOW_CTRL_CSR_INTR_FLAG;			/* clear intr flag */